fix plot legend checkbox selection to isolate change to current plot
fix plot legend checkbox selection to isolate change to current plot

mrakitin/sirepo,mrakitin/sirepo,mkeilman/sirepo,radiasoft/sirepo,mrakitin/sirepo,mkeilman/sirepo,mrakitin/sirepo,radiasoft/sirepo,radiasoft/sirepo,radiasoft/sirepo,mkeilman/sirepo,mkeilman/sirepo,radiasoft/sirepo